The Whole is Greater

Meshech Ḥochma notes that Parashat vaYakhel presents the building of the Tabernacle before the ark, while three Parashot previously, in Terumah, the order is the opposite.

Meshech Ḥochma explains that there are levels of sanctity higher than the sanctity of an individual Israelite. However, the sanctity of klal Yisrael (the totality of Israel) is unmatched. Thus, the Midrash [vaYikra Rabba 36:4, quoted by Rashi on Genesis 1:1] states that the entire world was created for Israel.

The Tabernacle represents klal Yisrael. Assembling the boards and covering them with the curtains to create a single tent represents the unity of Israel, the power of the klal. In Parashat Terumah the Torah presents the instruction to build the Tabernacle, it is not yet a reality. Therefore the Torah presents the vessels before the Tabernacle itself, corresponding to the higher sanctity of the ark than of individuals Israelites. However, in our Parasha, after the Tabernacle has actually been assembled, representing klal Yisrael, the ark has a lesser status and is presented after the Tabernacle.

Essentially, the Torah teaches us that in the case of the Tabernacle, as well as in the case of the People of Israel, the whole, as a collective entity is greater than the sum of the individual parts.